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Electronic and magnetic structures of hole doped trilayer La(4-x)Sr(x)Ni3O8 from first principles calculations

The magnetic and electronic properties of trilayer La4Ni3O8, similar to hole doped cuprates, are investigated by performing full-potential linearized augmented plane wave method-based spin-polarized calculations with LDA and GGA functionals including Hubbard U parameters to account for strong correlation effects. Based on these calculations, we found that La4Ni3O8 is a C-type antiferromagnetic (C-AFM) Mott insulator in agreement with previous experimental and theoretical observations. Our calculations suggest that Ni1+ and Ni2+ ions are found to be in high spin state with an average valency of +1.33. Intermediate band gap states are originated from dz2 electrons of both types of Ni ions after including the strong correlation effects. In order to understand the role of hole doping on electronic structure, phase stability, and magnetic properties of La4Ni3O8, similar calculations have been performed for La(4-x)Sr(x)Ni3O8 as a function of x, using the supercell approach. We have found that the hole doping brings insulator-to-metal transition without changing the C-AFM ordering though the magnetic moment is enhanced at both Ni sites. Moreover, these Ni atoms are always in an average valence state irrespective of hole doping or volume change. So the electronic properties of hole doped La4Ni3O8 can not be compared with hole doped cuprates which are high Tc.